Changing Effects on Java Image- Help!

Well, I'm sure that I am the 1000th person to ask a nooby question on this part of Hack Forums. Simply put, I need help doing some image processing in Java with Eclipse. I have created enough code so that my image opens up into a GUI and 4 buttons show up. My professor has started me with the 'negative' image effect that works correctly, but I can't seem to get other things to work (such as flipping the image horizontally or making the image go grayscale/black and white). If anyone can help me get started in the right direction or know a solution, that would be great. Below is the code, and, as you can tell, only the negativeButton works. The rest of the code under buttons such as bwButton, flipButton1, and flipButton2 is either copy/pasted or completely wrong as I have been playing around with no success.